case 885 does not engage any gears

helo all
am having a case 885 grader but its failing to load any gear thought the gear control lever seems to be loading properly. i have tried changing its transmission fluid but no change, i have also checked on the continuity from the ecu to the gear control lever and its all fine now i want to check on the hydraulic pressure sensors .
any one who could be having a solution to this problem please help out
thanks